1. Field of the Invention
This invention relates to the mixing and extrusion of thermo-plastic and thermo-setting materials. More particularly, this invention concerns screw or worm type apparatus for the mixing and extrusion of varied viscosity, natural and synthetic rubber and elastomeric material. Unless otherwise indicated, the term "extruder" as used herein, refers to and includes screw or worm type apparatus used to obtain an extrudate of desired cross-sectional configuration and/or for the mixing, blending, milling of thermo-plastic or thermo-setting compounds.
2. Description of the Prior Art
Conventional extruders include a barrel, a screw type rotor mounted within the barrel and adapted for rotational movement relative to the barrel and a means of introducing the material to be processed into the extruder, such as a hopper and its associated apparatus, if any. The rotor is provided with various threaded configurations, and rotational movement of the rotor relative to the barrel forces the material being processed through the barrel and out of the downstream end of the extruder. While the processed material is being discharged from one end of the extruder, hot or cold unprocessed material is fed into the feed hopper at the opposite end of the extruder to thereby make the extrusion process continuous.
Examples of the prior art are shown in my U.S. Pat. No. 3,632,255, dated Jan. 4, 1972 and my U.S. Pat. No. 3,375,549 dated Apr. 2, 1968. Another prior art patent of general interest is the Parshall and Geyer U.S. Pat. No. Re. 26,147 dated Jan. 24, 1967.
Although many problems relative to the extrusion of plastic materials have been solved, dispersion, blending and temperature control are continuing problems, by which the quality of extrusion is measured.